


A Dart of Blue

by Rubynye



Category: The Martian (2015), The Martian - All Media Types, The Martian - Andy Weir
Genre: 69 (Sex Position), Anal Sex, Ares3some, Clothed Sex, F/M, Light BDSM, M/M, Multi, Oral Sex, Polyamory, Threesome, Threesome - F/M/M, Vaginal Fingering, Vaginal Sex, bossiness
Language: English
Status: Completed
Published: 2016-02-01
Updated: 2016-02-01
Packaged: 2018-05-17 14:59:55
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 4,865
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/5875240
Author URL: https://archiveofourown.org/users/Rubynye/pseuds/Rubynye
Summary: <blockquote class="userstuff">
              <p>Beth knows how to stack a threesome.</p>
            </blockquote>





	A Dart of Blue

**Author's Note:**

> For Polyshipping Day!  
> You may have detected a theme in my story titles for this fandom.

When Mark gets up to, "And it'll be easier in .4 G," Beth knows she has to intervene. Chris is just kinda-listening, mostly-watching with a soppy smile on his face, slumped against the wall cradling Mark's head in his lap as Mark unreels the latest sex act they're going to enjoy indulging him in. Beth's curled at ease half-beside, half-atop Mark with her head on his bare chest and her legs slung across his clothed thighs, but now she blinks as a plan streams through her head like a perfect subroutine.

"Especially for Beck here since we'll both be sitting on him," Mark continues, and Beth swings her legs off and sits up. Chris startles, but the one she looks at is Mark as he stares up at her wide-eyed, mouth pressed shut, a little bit scared like he thinks he's finally gone too far.

Eventually he'll learn just how far she'll go, Beth thinks, inhaling for a proper dramatic pause. "Of course not," she starts, because she can be a little bit of a bitch, "We're not breaking his pelvis." Mark's eyes glint as his eyebrows tilt in together, and she grins helplessly, because she's not that much of a bitch. Chris's smile blooms again at the edge of her vision, but It's Mark's she watches, the sideways uptilt of his mouth and the shine in his crinkle-cornered eyes, as she says, "There's a much better way to put this together."

Mark hoists an eyebrow full of challenge, spreading his hands. "All right, Bethy Jo," he says just to be annoying, "enlighten me."

"Oh, I will." Beth gets out of bed. "Get up, both of you." Mark smirks a little wider as he pushes himself up.

Chris pouts, deliberately, adorably. "What did I do?" he asks as he scoots forward. _Fell in love with both of us_ is too true for teasing and _put us in the same bed so we fell in love too_ is something Beth's not at all ready to say yet, so she just tears her gaze away from him and reaches for the spare blanket she hasn't needed since he moved into her bunk. She doubles it over into a rough pillow, sets it on the bunk's edge, and tosses one of the actual pillows against the wall.

Then she stands, turns, and grabs Mark by the waist, squeezing his bare firm sides as he spreads his arms wide. Beth pushes him where she wants him, two steps backwards to the bed and then a solid shove so he falls prone, looking bemused, landing with a little huff. "I'm upside down," he complains, hips up on the folded blanket, head and shoulders denting the pillow.

"You stay there," Beth orders as she turns to Chris. "And you come here," she says, gripping his waistband with both hands. "Right here, yeah. Put Mark's legs over your shoulders."

"Maybe we're overdressed?" Chris obeys, of course, smiling at Mark who beams up at him and flings his heels into the air.

"This is a dry run," As she climbs back onto the bed Beth adds, to forestall the inevitable, "Yes, I know where the lube is. Positioning first." She swings a leg over Mark's hips and settles astride him, resting her shoulders on Chris's chest, her head on his shoulder as she reaches back, grips Mark's knees for leverage, and wiggles a bit, digging her own knees into the mattress.

She knows she's got it right when she rocks across the length of Mark's dick, hard through his sleep pants, when she gets to watch his mouth open around a little gasp and listens to Chris's answering inhale rush over her ear. "There we go," she says, with well-earned smugness.

"Holy fuck," Mark reaches up and grips her thighs, hands hot through her pants. "You're right, this is awesome. I'm supposed to be an engineer!"

Beth can't keep from wiggling in a teasing little circle, feeing Chris's chest rise against her back, watching Mark's stunned face. "I lost my virginity at MIT." More like got rid of it maybe too fast, but that's a story for later. Right now she slides her hands up further, behind Chris's neck, and feels her grin crease her cheeks as she soaks in this moment, Chris snuggling his face into her cheek, his lips soft on her jaw and his nose nudging just below her ear, and Mark spread out before them wide-eyed with admiration and lust. 

Then Mark gasps out, "You get off on this, don't you?" and it's Beth's turn to be stunned. "Having us both at your Beck, ha ha, and call?" Chris brushes his snickering mouth across her cheek, as her face burns beneath his tender kiss and Mark smiles openmouthed in delighted discovery. "And I called _him_ bossy."

Well Chris can be, but not generally with her. "I like getting what I want," Beth dredges up to answer Mark's challenge. 

He squeezes her thighs, sliding his hands up, mapping her hips up to her waist. "Oh, baby," he murmurs, looking so warmly delighted she can't find it in herself to be annoyed, "come here and let me give you what you want."

"Should make you say 'please'," she fake-grumps, already slipping her hands from Chris's nape and tilting a little to swing her leg back over. Mark doesn't let go so much as shift his hold as she shuffles forward, his hands sliding up beneath her shirt to spread over her shoulder blades as she leans in over him. 

"Please," Mark breathes, his eyes glinting from half-lowered lids, and licks his lips, leaving them shiny wet. "Beth, please," and she tips forward and kisses him hard until her own mouth tingles, until he moans throatily, closing her teeth on his bottom lip as she pulls back to remind him who's in charge here. 

Then she pushes herself upright, and turns, swinging her knee across Mark's shoulder, and as his big hands peel her pants down she looks up at Chris, who's smiling wide and warm at their spectacle. He stayed where Beth left him, standing with Mark's legs slung over his shoulders, tilting Mark's hips up towards her. As she tries to decide what to go for first Mark drags his tongue in a long hot flexing lick, moaning into her like she's delicious, and she shivers and instinctively reaches for Chris.

Chris takes her hand, meshing their fingers, and sinks to his knees, holding Mark's thigh in place. Mark hums a question and Beth wiggles on his face, feeling herself ride his nose and his toothy smile before he sucks one of her labia and sparks rush up her spine. She gasps, dropping her head, and Chris tugs her hand a little; she manages to hoist her head up, and his eyes glitter as he hauls Mark's waistband up and over his rearing dick.

Beth grins, shakily, because Mark has gotten going in earnest, broad hands clamped around her hips as he licks and sucks and works delightfully earnestly at driving her wild. Little crackles already edge her mind as Chris leans in and kisses her lavishly to match, and Beth moans, gripping the mattress, squeezing his fingers as she shudders between them. When Chris pulls his mouth from hers she's already panting, another moan pushing up out of her, and she muffles it into a wet kiss to Mark's salt-damp shaft.

Mark moans low, buzzing into her as he closes his lips around her clit, and Beth cries out around his dick. Chris kisses her around Mark, lips meeting as they lick around the curve, and Mark wails into her, high and wild as Beth whimpers in answer. She manages to get her mouth over the head but pretty much just sobs and sucks with no finesse, sprawled across Mark's front; he moans and moans, his chest heaving and belly tensing beneath her, but hangs onto his pattern, licking lushly across her clit over and over, caress by curling caress until she screams around him as she comes, shaking from that center outward until even her hair seems to tingle.

Chris hums and pulls his fingers from hers to pet her hair back from her face, and she gives up, pulls her mouth off Mark and flops over panting, dredging up the strength to dismount. But Mark tightens his grip on her thighs and keeps going, moaning on every breath, and Chris winks at her as he pushes the plump pink ring of his lips down Mark's dick. Mark's chest hitches, Beth smiles around her gasps and reaches up to push Chris's bangs back in his turn, sliding her hand down his hollowed cheek, over his stretched lips and down. Riffling her fingertips through crisp wet curls, she wraps her fingers around the base, steadying it for Chris, and as he bobs he brushes his plush lips over her hand, a sopping openmouthed kiss. Mark groans deep and suckles harder and Beth throbs, her clit and her cunt as she squeezes tight with sheer sensation, her thighs under his clutching hands, her nipples and ears and toes and every last bit of her entire body as she comes again, dropping her forehead to the mattress, her fingers fluttering as she shouts with each pulse.

The first thing she hears beside her own pounding heartbeat is Chris snuffling and sucking hard. He pets her cheek, his eyes pressed shut, urgently dipping two fingers between her lips, and Beth grabs his wrist and licks his whole hand palm to fingertips, as best as she can while still breathless. Chris pulls his hand back and Beth wishes she could reach over the bed's edge to stroke him, but her arm's definitely not that long. She settles for stroking Mark a little, up and down a couple inches as Chris sucks with noisy force; Mark cries out against her flesh, his belly tensing rock-hard, and Beth manages to shift her hips up, unmuffling him just in time for him to wail a high broken noise, his fingers sliding up tight around her waist, his dick jerking in her hold, Chris's eyelashes fluttering and throat bobbing as he swallows over and over.

When Mark subsides from wails to whimpers, Chris pulls off, butting his forehead against Mark's thigh as he pants openmouthed, shoulder rolling as he strokes himself. Beth pets her easing handful and lays him down gently, watching furrows crinkle across Chris's forehead as he groans between clenched teeth. He huffs, his voice sinking deep, and Beth watches his shoulders shake and the tension ripple across his face and finally fade away, leaving him limp with his cheek pressed to Mark's thigh.

Mark pries his grip off Beth's waist and she slumps sideways, ignoring her waistband around her knees, still watching Chris. She could grab for her pants but presentability seems really far down the priority list compared to Mark's hand draped across her back as he breathes out little incoherent happy noises, to every tiny shift of Chris's face as he shudders through a couple of aftershocks, licks his outslung lip, and finally smiles, slowly opening his eyes, looking up through his lashes at her.

Then he glances down, smile twisting wryly as his arm turns. Beth can't see his messy hand but she can add it up. "Guess I should've seen that coming," he mutters huskily, voice rough and low, and she tingles all over like she can feel the sound waves. She could totally go for another round, pulling Chris back into bed, leaning back into Mark's arms as she strokes Chris up into fucking her. If they didn't have a full day tomorrow, of course, if they shouldn't already be asleep.

"Wish I could've seen you coming," Mark rumbles, and Beth startles around a little shard of worry, glancing back, wondering if she should've -- "but the view was so fine," Mark goes on, and she can't see his face because he's curling sideways, just before he presses a firm kiss under the curve of her asscheek, startling a gasp out of her.

"Yeah, it definitely is," Chris murmurs, looking up at Beth again, into her, and she giggles, a little embarrassed, more than a little happy. He brushes his lips across hers as he pushes himself up, dropping his pants as he goes, and grabs a washcloth from the bedside stack. A moment's scrubbing leaves him looking dissatisfied at his hand before he grabs his shirt and pulls it off. "Unf, first wash-up."

"Third," Beth calls, nodding, watching Chris head for the lav cubicle. Time to clean up. As she grabs a washcloth too she gets her knees beneath her and turns herself around, kicking off her pants. Mark is picking his front teeth and looking extremely pleased with himself, and she drops the cloth on his shiny wet face. 

He swipes it across his face a few times, tilting his chin up, eyes dark and glittering, and she leans in and kisses him, tasting her own musk on his smiling mouth. He pushes up into the kiss and she pushes back, opening her lips over his, tasting herself on his tongue; he wraps his arm around her, hand sliding down over the small of her back to curve under her ass in an impertinent squeeze.

Beth doesn't let herself squeak. She plants her hand beside Mark's head, pushes back from his inviting mouth, and reaches behind her to firmly pull his hand up to her waist, precisely because she wants him to squeeze her some more.

Mark just grins. "What's that position called anyway?" Beth hadn't thought of that; she shrugs and his grin widens. "How about the Martian Wheelbarrow?" makes her crack up laughing. 

"Yeah, that works." She laughs, and feels Mark watching her, gets herself propped on her elbow and smiles at him, warm from her core outwards. 

His, "Bossy looks good on you," just warms her more, without the blush she would've thought those words would cause. 

"Someone has to take charge sometimes." Beth wants to drop her chin shyly but she keeps it raised, keeps watching Mark's eyes as they crinkle at the corners.

"I like how you take charge," Mark tells her, running his fingertips up and down her spine. "Beck sure does too."

"Really?" Beth asks, mostly as a tease. She knows Chris likes it. She could feel how much Mark does. "Because you didn't exactly just follow orders, there."

"Think you could make me?" Mark asks, challenge in his lifted chin, hope in his bared throat.

Unusually, utterly sure, Beth wraps her hand around Mark's throat, thumb pressing just slightly where his jaw joins his neck, forefinger up beneath his ear. "Yeah," she tells him, as his sleepy eyes flare wide. "I think I can."

"Keeping him in line?" Chris asks behind her, and she watches Mark's snub nose twitch and feels herself grin as she nods.

"Doing my best." Beth tucks her hand behind Mark's nape and tugs. "Your turn, Watney."

"Awww," Mark fake-pouts, but sits up under her hand, kicking off his pants. Scooting sideways, she plants both hands on his shoulderblades and pushes until he gets to his feet. As they pass each other Chris pats his arm and Mark swings his hand back to smack Chris on the ass, and Beth has to smother a giggle, watching Chris's big eyes go round.

"Gonna remember that at your next exam!" Chris calls over his shoulder, smacking his lips in a glove-snapping noise, and Mark 'eeep's and runs for the lav's dubious shelter. Trading a smile with Beth, Chris scoops up their scattered clothes and sorts them out, tossing his shirt at the hamper, pulling his pants back on, and Beth watches him shift and move and breathe, because she can.

She strips off her damp tee and hands it to him, since he's a better shot, and after he tosses it too he reaches to stroke her hair. "I'm all sticky," she warns his freshly sponged-down self.

"You're magnificent," Chris replies, giving her that soppy delightful smile, and kisses her forehead. "You looked amazing sitting on Mark's face." Beth blushes a little, and Chris kisses each of her cheeks. "I bet you look that incredible sitting on mine."

"My face is gonna catch fire," she mutters, and Chris laughs lightly over her mouth and kisses her, warmly, languidly. She doesn't let herself scoot closer because she really is sticky, but she leans into the kiss, into Chris's hand on her cheek, into his comfortable sensual warmth as they make out until her lips tingle, until her breath catches, until he makes the sweetest little deep noise and presses all the more towards her.

Until she hears a third breath, and she and Chris turn to find Mark leaning beside the door, smiling at them with dark eyes. "Look at you two," he murmurs fondly, but there's a little line sunk between his eyebrows. "Can a guy get a goodnight kiss?"

Some nights Mark goes back to his own quarters, some nights one or both of them join him there, some nights he doesn't come over, it all depends. Beth looks up at Mark as she nods to him, and glances at Chris, who meets her eyes and nods to her before looking forward as Mark steps towards them. He kisses Chris first, which works with her plan; when he kisses her she grips the hair just above his nape and feels his gasp rush between their lips, smiles over his mouth and murmurs, "Get into bed, Mark."

Mark folds right down between them, and Beth stands as he lies down, settling him with both hands. "Back in a minute," she says, and both Chris and Mark look up at her with big eyes, like they're impressed. Maybe even worshipful. 

Maybe she's just flattering herself, but either way, she likes how they look at her. She likes getting what she wants, Beth allows herself, lets herself enjoy the thought as she goes to wash up. And she likes it all the more when she comes back to find Chris leaning over Mark, kissing him gently, Mark's hands draped at ease on Chris's shoulders, Chris's lips moving in languid caresses as Mark melts a little more into the mattress. They kiss, and pull back smiling, scooting apart just far enough to make space for her.

Beth pulls on her pants, doesn't bother with a shirt, climbs over Chris and snuggles in. "Reconvene in 46 hours?" she asks, resting her cheek on Chris's chest, smiling as Mark wraps his arm around her just under her breasts.

"God willing and none of the temp sensors rise," Mark murmurs drowsily, Chris hums affirmation, and Beth smiles all the way into sleep.

***** 

It ends up being 69.25 hours, but they try it again, without their clothes this time, and it works just about perfectly. As Mark shudders down from coming Beth leans straight-armed down on his shoulders, pressing him down bracingly hard as she watches his face, his crinkled forehead, the tears running from his squeezed-shut eyes, his trembling mouth. Mark sobs out fervent little _oh_ s as Chris grunts on each thrust, really pounding it home now, jolting through them both. Beth rides the thrusts and grips Mark's shoulders, pins his hands a little more tightly behind her knees and watches him soak up all the sensation they can pour into him. She loves it when they get him so worked up he cries, his shoulders shaking in her grip, his belly heaving against hers. She loves that he'll let them see it. She bears down around him and Mark shouts, arching his neck; she wants to bite his bared throat, she dents her nails into his shoulders and deliberately squeezes around him again, and he hollers, "Fucking God, Beth, Chris, Beth!"

"Yeah," Beth breathes, as Chris groans low and smacks hard into Mark, who wails so loud she feels her cheeks tingle hot, thank goodness and their crewmates for the soundproofing lining the walls. "Shh, yeah, we're here." She deliberately wrings around his cock still inside her and feels him try to writhe, listens to his moans rise, hears and feels Chris groan as he feels Mark reacting to her. "Mm, feel that? Feel Chris?" It's a whirling feedback loop until Chris slumps forward, pressing his forehead between Beth's shoulderblades, his voice breaking into sharp cries. "There you go, both of you. There you go." Beth slides an arm back, tucks her hand between Mark's trembling thigh and Chris's heaving ribs, and feels each pulse go through both of them. 

Mark shivers under her, staying exactly where she's pressed him even when she lifts both hands to adjust her position. He gasps, spread out for them, eyes shut tight, and she rocks forward to him, letting up on his hands, leaning down to settle hers either side of his head. His lips tremble around ragged breaths, and as Chris rests his broad hand behind her heart she brushes her smile over Mark's open mouth. He pushes up desperately, flipping his hands to cup her thighs as Chris sweeps her hair up and kisses her nape, and as she kisses Mark she hears Chris pull out on a slick little sound, feels Mark's answering shudder, coolness opening across her back as Chris staggers away with a quiet huff. She keeps the kisses soft, over and over as Mark's chest steadies into even breaths, up and down, until his shaking fades out and he kisses her tenderly back.

"Beth," Mark mutters against her lips, low and rough, and she shifts up just far enough to let him talk, nose alongside nose, his mouth brushing her cheek as Chris moves behind them. "Beth?"

"Yeah, I'm here," she murmurs over his cheekbone, skimming her lips across salt-wet skin, feeling him still breathing hard enough to shift her up and down. 

"Can I?" Mark puffs, sliding his hands back, cradling her bottom delicately. "Please, can I?" 

His fingertips brush her wet inner thighs, and she pulses with desire, knowing what he's asking, what he's offering, but. But. Taking a deep cooling breath, Beth nudges Mark's nose with hers as she says, clearly as she can manage, "Words, Mark." Chris makes a little approving sound behind her. "Can you what?"

Mark's forehead creases, his eyelids crinkle and smooth back out again. "Please, can I touch you?" He sucks in a shuddering breath and exhales soft begging over her mouth. "Can I make you come again? Please let me, Beth, please."

Heat curls and throbs inside her, gripping her like she wants to grip him, shoving her forward to kiss him hard, her lips sparking sore. He gasps into it, she growls, "Yes," and he gasps again, edged with a cry, as she kisses him as hard as she can, her mouth burning against his. His clever fingers slide inwards, stroking her open, two slipping wetly inside her as his thumb presses just _perfectly_ and she groans and bites his lip.

The bed dips under Chris's warm weight, he slides a hand across Beth's back to grip Mark's arm, and Mark moans into her mouth and strokes her more insistently, cupping her thigh to support her. Chris's arm presses across her back as she tingles all over, around Mark's fingers inside her, already almost ready to come again. it's not like she cooled off any, riding Mark as he moaned for them, watching his every quiver as they fucked him. Now she writhes, grinding down onto his hand, dragging her aching nipples along his sweat-slicked chest; Chris leans in to run his teeth along the rim of her ear, she clenches down on Mark's fingers and he whimpers and that's it, that's it. Beth feels the wild fluttering within her, out of her conscious control, as she comes again, crying out on every pulse.

As she trembles back to awareness Beth sinks down so slowly, trading gasps with Mark, their noses touching. Delight fades to discomfort, and Beth drags up a hand to pat Mark's chest; he nods briefly, easing his fingers out of her, lifting his less-sticky hand to grip her shoulder and help push her up. She tips forward-sideways and Chris catches her, leaning her back onto his chest, and she reaches out with what seems like the last of her strength and tucks her hand behind Mark's nape. He scrambles up the bed to her, panting much more forcefully than from just a shift up the bed; she closes her eyes as she leans Mark's forehead against hers and he throws his arm across her waist and Chris's, still trembling as they all hang onto each other, cooling down together back to calm.

Eventually Mark shuts his mouth and clears his throat and shifts back a few inches, and Beth lets go of him. He doesn't let go of her and Chris, though, and while he says, "So some MIT super nerd taught you how to stack a threesome?" with his usual dry cheer, she can still hear a tremor in his voice.

She smiles, welling up with warm tenderness to match Chris's solid warmth at her back, and wants to pull Mark back in, trading off with Chris to kiss him gently over and over. Instead she puts some teeth into her grin and answers, firmly as she can, "Yep, my first girlfriend." There's a wobble in her voice too, and Chris tucks his other arm up around her. She slips her heel back in answer, pulling her foot up along his calf in a grateful caress.

It takes Mark an extra beat but he comes in with, "Ooh, I wanna hear this!" pretty much on cue, and Beth has to smile even wider, she'd laugh if she had the energy.

Instead she gets her heavy eyelids up enough to look at Mark smiling at her, his eyes dark and calm and sleepy in his turn. "You want," she manages with a weak attempt at sternness that makes Chris stifle a snorted laugh against her shoulder, "me to tell you the tender details of my first adult sexual relationship, for your jerk-off pleasures?" 

"Hell yes," Mark hoists an eyebrow, and Beth does crack up laughing, Chris vibrating with chuckles all down her back as Mark's smirk widens. 

"Should hit you with the pillow," Beth tries to snap. The threat's pretty empty when her arms feel like noodles. Mark breathes out a little 'heh' and pulls his hand from under his head to drop it beside hers. "Maybe I'll tell you later," she says sternly, making herself a liar by meshing her fingers with Mark's, "if you behave."

Chris laughs his opinion of that into her throat, kissing her under her chin, as Mark's eyes crinkle further. "Oh I'll behave," he murmurs, warm with mischief. "Like a man with visions of nerdy lesbian collegiate sex dancing through my head."

There's only one answer to that, really, noodle arms or no. Beth reaches back, hauls the pillow out from behind Chris, and gently thwacks Mark's laughing face with it, once, twice, thrice until she starts laughing again too. Mark tips back towards her, Chris grips his bicep as they cuddle together, warm skin pressed to skin, all of them vibrating on the same cheerful frequency.

Chris recovers first, enough to gasp out between chuckles, "Okay, okay, cleanup time. We should --"

Maybe Mark's mischief is infectious, but Beth doesn't feel like being responsible quite yet. "We should put _you_ in the middle next time," she says, twisting around to watch Chris's eyes flare round and bright, hs eyebrows arching up as Mark hums a knowing little _mmm-hmm!_. 

She knew he'd like that, she grins as he kisses her cheek, her nose, her upper lip. As she kisses back properly, Mark leans his damp head on her shoulder and exhales a soft deep noise, both happy and hopeful. Chris exhales contentment as he pulls back enough to look at her again, and she basks in the warm deep light in his eyes, leans into his solid chest as he presses forward to kiss Mark too.

Eventually, Mark sighs a sated, sleepy noise and slumps onto his back. "Watney, going offline," he announces, voice slurred with pleased exhaustion.

Beth can sympathize, well-earned weariness tugging at every gram of her. She pillows herself on Mark's slight but noticeable pec, draping her hand across his ribs, feeling the flesh padding their formerly gaunt framework. Pushing her eyes open one more time she looks up at Chris looking fondly at them, and he leans down to tuck his smile into her hair and tangle his legs with hers and Mark's.

"Honestly," Chris murmurs, "I think I'd like to be on my knees, if I could. What do you think, Mission Planner?"

Beth closes her eyes to see the images flashing through her mind, angles and forces and arrangements and so much delicious porn. "Think I can work with that," she murmurs, wiggling just enough to feel herself tucked securely between Mark and Chris, her cheek sliding along Mark's skin as she smiles.


End file.
